This clinical protocol will examine measures of heart rate variability (HRV) in male and female alcoholics admitted for drinking cessation continuously and non-invasively. These measures will be compared and contrasted with HRV parameters studied in healthy comparison subjects. Inter-beat interval (IBI) will be measured in patients for 3 consecutive 96 hours periods every 7 days during the course of treatment. Coarse-graining spectral analysis (CGSA) will be utilized to simultaneously evaluate parasympathetic (PNS) and sympathetic (SNS) nervous system indicators, and a measure of signal complexity and variability.